An area of improvement in the additive manufacturing (AM) of metal and ceramic materials space is the ability to produce geometrically complex parts quickly and with high precision. Presently, finished parts often have significant porosity since there is limited means to control the packing of powder during printing. Moreover, current methods are designed for spreading a single material. One way of packing powder is through the use of vibration. The challenge in this approach is to apply vibrations to powder deposited on the substate without disturbing the geometry of the printed structure. The LLNL invention was able to overcome this challenge.
LLNL researchers have developed a piezo-driven jetting powder AM method that provides better control of the packing of printed powder. Powder is fed via a stainless-steel hopper to a nozzle; at the narrowest necking point the powder jams, and flow ceases. A vibrating piezoelectric element (with through-thickness vibration mode) is driven by a 150V AC signal to disturb the jammed powder, allowing it to flow through the narrow nozzle. This flow can thus be turned on and off via the piezo, and flow rates can be controlled via signal frequency, nozzle size, and powder properties. The coupling of the piezo to the nozzle is engineered for maximum vibration at the powder jamming point and at the nozzle tip to compact particles after deposition. The powder is confined between the nozzle and substrate, and as the nozzle is moved, it scrapes and vibrates against the powder, rearranging particles and compacting them.
Current stage of technology development: TRL 3
LLNL has filed for patent protection on this invention.
- Value Proposition: Controlled packing density for powder deposition
- Increased packing density directly increases the performance of deposited walls in complex geometries
- Reduced porosity or spatially modulated porosity, slumping and defects
- Applicable to both metal and ceramic powders
- Lower material waste
- Powder spreading for metal/ceramic additive manufacturing
- Multi-material powder beds for SLM or binder jet printing
- Printing pre-forms for hot pressing parts with non-uniform thickness
- Multi-material hot-pressing pre-forms
- Agricultural, geotechnical, pharmaceutical powder dispensing onto substrates or cavities with controlled density
